T-square.



u. GRl FFITHS.

I-SQUARE. IAPPUGATION FILED MAY 25. 1912.

1,28,711 Patented Junm, 191s.

.fLs

WITNESS TED s'rATEs T-SQUARE.

Specification of Letters Patent.

Patented June a, 191.

Application filed May 25, 1917. Serial No. 170,938.

To all whom it may concern:

' Be it known that I, DANIEL GRIFFITHS, a

citizen of the United States, residing at Pittsburgh, in the county ofAllegheny and State of Pennsylvania, have invented new and usefulImprovements in T-Squares, of

which the following is a specification.

This invention relates to a T-square and has for its primary object toprovide a device of this character b means of which lines can be drawnat di erent angles.

An object of the invention is the novel manner of connecting the bladeto the head whereby upon reversing the blade connection with the headthe blade may be rigidly connected to the head or connected thereto forpivotal movements.

With these and other objects in view the invention will be betterunderstood from the following detail description taken in connectionwith the accompanying drawing wherein:

Figure 1 is a top plan view of the T-square. Figs. 2 and 3 are sectionalviews on the 7 line w-a of Fig. 1 showing the two positions of theblade.

Figs. 4 and 5 are detailed views of a modified .form of the invention.

Again referring to the drawing the numeral 1 designates the head of theT-square formed centrally with a slot 2 shown in this particularinstance as rectangular in shape, although various other shaped slotsmay be used. The blade 3 upon one side is formed with a rib 4, snuglyreceived in the recess when the blade is to be rigidly secured to thehead. At this point I wish to call attention to the fact that the headand blade may be made of a light metal such as alumiwidth of the slot itwill be seen that when the blade is reversed as shown in Fig. 3 theblade is free to have pivotal movements relative to the head.

In Figs. 4 and 5 I have shown the blade 6 so constructed that it will beonly necessary to loosen the thumb bolt when reversing the blade and toaccomplish this result the blade is formed with a passage 7 forreceiving the shank of the bolt and depressions 8 for receiving the headof the bolt. As this passage is open at the adjacent end of the blade itwill be seen that by slightly loosening the nut the blade will be freeto 0 slide from under the head of the bolt.

From the foregoing description taken in connection with the accompanyingdrawing it should be apparent that I provide a device that is admirablyadapted for the pur- 5 pose in View in which the parts are substantiallyconstructed and that may be men ufactured and sold at a comparativelylow cost.

What I claim is: T-square comprising a head having a slot a blade of awidth greater than the width of the slot and having centrally locatedupon one side a rib of a width equal to the width of slot and adapted tobe seated 7B in said slot in a predetermined position of the blade and asecuring element passing through the blade, rib and head.

In testimony whereof I afiix my signature.

DANIEL GRIFFITHS.

(topics o1 this patent may be obtained to! live cents each, byaddressing the "commissioner of Retentn.

Washington, D. 0."

